1. Anatomy and Physiology
Marieb’s Human
Anatomy and Physiology
Ninth Edition
Marieb w Hoehn
Chapter 27
Male Reproductive System
Lecture 18
Part 1: Overview and Primary Sex Organs
Slides 1-15; 80 min (with review of syllabus and Web sites) [Lecture 1]
Slides 16 – 38; 50 min [Lecture 2]
118 min (38 slides plus review of course Web sites and syllabus)

2. Warning! The video and narration in this presentation concerns the
Male Reproductive System
and uses explicit graphics and terminology dealing with this subject matter.
Some material may not be suitable for younger viewers.
Slides 1-15; 80 min (with review of syllabus and Web sites) [Lecture 1]
Slides 16 – 38; 50 min [Lecture 2]
118 min (38 slides plus review of course Web sites and syllabus)

3. Male Reproductive System
There are three main functions of the male reproductive system
Produce and maintain sex cells (sperm)
Transport sperm and supplemental fluids to the female reproductive tract
Secrete male sex hormones
Sex organs can be divided into
Primary sex organs (gonads) = testes (sperm, hormones)
Accessory (secondary) sex organs = internal and external reproductive organs
In order for sexual reproduction to take place, we need: 1) mobile cells, 2) cells that are nutrient laden. These two things are impractical to combine into one cell, so males have sperm (DNA with propellers!!), and females have large, nutrient-laden eggs as their sex cells (gametes).

4. Male Reproductive System
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Testis → Epididymis → Vas (ductus) deferens → Ejaculatory duct → Urethra

5. Male Reproductive Organs
posterior view
Figure from: Hole’s Human A&P, 12th edition, 2010

6. Descent of Testes
Figure from: Hole’s Human A&P, 12th edition, 2010
Descent begins 1-2 months before birth under the influence of testosterone
Descent is necessary for sperm production
Failure of testes to descend = cryptorchidism

7. Structure of the Testis
Figure from: Hole’s Human A&P, 12th edition, 2010
Surrounded by the tunica albuginea – a tough, white, fibrous capsule that encloses each testicle
Septa divide each testicle into about 250 lobules
Each lobule contains 1-4 highly coiled seminiferous tubules that give rise to sperm
Interstitial cells (of Leydig) lie in between seminiferous tubules and secrete male sex hormones
Rete Testis

8. Review of Mitosis and Meiosis
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Major differences between mitosis and meiosis: 1) mitosis produces identical daughter cells, meiosis produces cells with recombined DNA; 2) daughter cells in mitosis have a diploid number of chromosomes whereas in meiosis gametes contain the haploid chromosome number; 3) two daughter cells are produced as a result of mitosis, whereas four cells are produced after meiosis.
Mitosis – production of two identical diploid daughter cells
Meiosis – production of four genetically varied, haploid gametes

9. Chromosome Crossing Over
Figure from: Hole’s Human A&P, 12th edition, 2010
mixes up traits
different colors represent the fact that one homologous chromosome comes from the individual’s father (paternal) and one from the mother (maternal)
Tetrad
the genetic information in sperm cells and egg cells varies from cell to cell

10. Seminiferous Tubules and Sperm Maturation
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
It takes about 75 days for a spermatogonium to become mature spermatazoon.
Spermatogonium = stem cell

11. Spermatogenesis Spermatogonium (2n) Primary spermatocyte (2n)
Know the order of events below!
Spermatogonium (2n)
Primary spermatocyte (2n)
Meiosis I
Secondary spermatocyte (n)
Meiosis II
Spermatid (n)
Spermiogenesis
Spermatozoan (n)

12. Formation of Sperm Cells
Figure from: Hole’s Human A&P, 12th edition, 2010
Supporting cells are sustentacular cells
They:
are important in regulating and supporting spermatogenesis
help maintain the blood-testis barrier

13. Structure of a Sperm Cell
Figure from: Hole’s Human A&P, 12th edition, 2010
Only flagellum in human body
Mitochondria
Young men produce about 300,000 sperm per MINUTE, or about 4 million sperm cells per day.
Enzymes used to penetrate the egg during fertilization

14. Review Spermatogenesis Spermatozoa
Spermatogonia, 1o spermatocyte, 2o spermatocyte, spermatid, spermatozoan
Is a result of meiotic division
Under the control of FSH
Is guided and regulated by sustentacular cells
Produces 4 haploid gametes (spermatozoa)
Spermatozoa
Head, midpiece, and tail
Acrosomal cap – enzymes use for fertilization
Non-motile when produced – must undergo capacitation